Lorient in 2019 Meslier began playing football with his local club Merlevenez at the age of 6, and after a successful match against
FC Lorient joined their academy. On 1 February 2018, he signed his first professional contract with Lorient. In July 2018, Lorient rejected a €10 million bid from
Ligue 1 side
AS Monaco for Meslier. He also received interest from English
Premier League side
Chelsea. He kept a clean sheet consecutively in his first five games as a professional, conceding his first ever goal in his 6th game against
Paris FC. He saved an injury time penalty from
Clermont player
Manuel Perez in Lorient's 1–0 win against Clermont. He solidified his place as the club's number 1 keeper during the 2018–19 season, playing 30 times in all competitions, keeping 11 clean sheets. With his form helping Lorient finish in 6th in
2018–19 Ligue 2 but narrowly missing out on the playoffs due to goal difference compared with
RC Lens.
Leeds United 2019–20 season On 8 August 2019, Meslier moved to England and signed for then
EFL Championship club
Leeds United, on a season-long loan, with Leeds also having the option to buy Meslier on a permanent deal. He started the season as second-choice goalkeeper behind
Kiko Casilla and competing with
Kamil Miazek for a place on the bench, and Meslier gained a reputation as a penalty saving expert after saving three separate penalties for
Leeds United under-23's by December that year. On 4 January 2020, then head coach
Marcelo Bielsa announced that Meslier would make his debut on 6 January in Leeds'
FA Cup tie against
Premier League side
Arsenal. With Meslier putting in an impressive performance against the Premier League side in a 1–0 defeat on his debut, he was praised for his distribution and his saves during the match. On 29 February 2020, he made his league debut for Leeds in a 4–0 victory away at
Hull City. Meslier finished the season as first choice at Leeds after an eight-game suspension to fellow goalkeeper Kiko Casilla, with Meslier keeping seven clean sheets in his 10 league games to help Leeds become Champions and win promotion to the Premier League.
2020–21 season On 23 July 2020, Meslier joined Leeds permanently following their promotion to the English
Premier League, for a reported £5m transfer fee, signing a three-year contract. Meslier made his
2020–21 Premier League debut in the first match of the season against
Liverpool on 12 September 2020, starting in the 3–4 defeat at
Anfield to the reigning champions. On 28 September, Meslier was named man of the match in the Yorkshire derby 1–0 win over
Sheffield United at
Bramall Lane, after making a string of fine saves including a point blank reflex save at 0–0. On 23 February 2021, Meslier became the first goalkeeper under the age of 21 to record 11 clean sheets in a single Premier League season, eventually finishing the season with 11.
2021–22 season On 13 August 2021, Meslier had signed a new deal with the club, which triggered an extension to his contract running until 2026.
2022–23 season Meslier's performance against
Liverpool on 29 October 2022, in which he made nine saves to give his side a 2–1 away win and take them out of the relegation zone, saw him awarded the Premier League Man of the Match award. He made his 100th appearance for Leeds at home on 4 January 2023, in a 2–2 draw with
West Ham United. Meslier conceded 22 goals in seven games during the month of
April that year, during which the team took just four points from a possible 21 and resulted in the dismissal of head coach
Javi Gracia. With the arrival of
Sam Allardyce in May 2023 — Leeds’ fourth manager of the 2022–23 season — Meslier saw no further action in the first team, being replaced by
Joel Robles for the final four games of the season, from which the team gained a single point, demoting the side to the
EFL Championship for the following season.
2023–24 season Under newly appointed Leeds manager
Daniel Farke, Meslier returned to being first-choice goalkeeper in the Championship. On 26 December 2023, Meslier received a red card after pushing
Milutin Osmajić in the face in a match against
Preston North End. Leeds finished 3rd overall in the Championship season, qualifying for the playoffs and making it through to the playoff final at
Wembley Stadium for a chance to return to the Premier League. Meslier started the playoff final against
Southampton, in which Leeds lost 1–0 to stay in the Championship.
2024–25 season Meslier remained as first-choice goalkeeper for Leeds in the
2024–25 season under Farke, playing in 39 of a possible 46 league matches as his side finished as Champions and earned direct promotion back into the
Premier League. However, he was dropped for the final 7 matches of the season in favour of
Karl Darlow after an error-filled performance on 29 March 2025 against
Swansea City, leading to speculation over his future at the club.
2025–26 season Leeds' return to the Premier League sparked some significant player movement in and out within the squad, including the transfer of goalkeeper
Lucas Perri from
Ligue 1 club
Lyon for a reported £15.6 million fee, igniting rumours that Meslier's exit from the club was imminent. Boyhood club
Lorient and Italian
Serie A side
Como were rumoured to be considering bids for Meslier, but by the end of the summer transfer window no transfer emerged. Meslier was registered in the Leeds squad for the 2025–26 season, but is considered to be third-choice goalkeeper behind Perri and Darlow and was assigned the number 16 shirt after Perri claimed the number 1, the number Meslier had worn at the club since his arrival in 2019. ==International career==